In 2016, Toyota started to experiment with placing solar panels on the Prius in Japan. Despite the obvious benefits, the aesthetics of such an approach were always going to be a challenge. There were limitations on the placement of the panels and consequently the amount of energy they could provide. Fast forward to 2019 and panels are much thinner and flexible meaning that more space on the car can be covered by them, and battery cells are just 0.03mm thick. This allows much more energy to be generated and can charge while the car or both stationery or moving.
The net result is a further 27 miles in driving range, which is just under the average daily commute in the UK. Road trials by Toyota, Sharp (batteries) and NEDO (a research and development organisation) are due to commence following positive test trials. The ultimate goal of solar providing a solid proportion of an EV's energy requirements is now a little closer.
Sources
https://techxplore.com/news/2019-07-toyota-solar-panels-electric-cars.html
Thomas Industry: https://bit.ly/2GmcU7v